Engineering materials and manufacturing process

1. Engineering Material &
Manufacturing Processes
Prof.A.B.Humbe

2. Engineering Materials
• Introduction
The knowledge of material and their properties are great significance for
engineer. The machine parts should be made of such a material which has
properties suitable for the conditions of operation.

3. Classification of materials
Solid materials are grouped into three basic groups such as metals, ceramics and polymers
this grouping is based primarily on chemical makeup and atomic structure in addition to this
there are other three groups of engineering materials composites, semiconductor and bio
materials
1.Metals
-Metals are the backbone of industrialization.
-Metals have very wide application in the almost every engineering discipline.
-Metals are quite strong deformable which accounts for the use in various application.
-Alloying elements together have yielded a large variety of metallic materials

4. There are two types of metals
i)Ferrous metals: - Ferrous metals consist mainly of iron with comparatively small
addition of other materials.
-Ferrous materials are iron and its alloys such as cast-iron, grey cast iron, malleable
cast iron, wrought iron and Steels offer low carbon content and high carbon content
etc
ii)Nonferrous metals: - Nonferrous metals contains little or no iron the materials
include aluminium, magnesium, copper, zinc, tin, lead, nickel, titanium and so on
and their alloys

5. 2.Ceramics: - Ceramics are mostly oxides, nitrites and carbides.
- These are compounds between metallic and non-metallic elements.
- Ceramic can withstand at high temperature and harsh environment than metals
and polymers.
- These are electrically insulating materials. Ceramics are heat resistant materials.
- These materials are hard but highly brittle.
- Some of the ceramic’s materials are Aluminium oxide tungsten carbide, silicon
carbide, cement concrete, glasses, granite, magnesium oxide, calcite, boron tetra
nitride etc

6. 3.Polymers: - A polymer is composed of a large number of repetitive small
chemical units called monomers for simple molecules.
-It is made up of thousands of monomers joined chemically together to form a large
molecule.
-Polymers include the plastic and Rubber materials. These materials are extremely
flexible and have low densities.
-Some of the well-known Polymers are rubber, poly vinyl chloride, polythene,
terylene, nylon, teflon, acrylic etc

7. 4.Composites: - Sometimes two or more materials are combined together to
produce a new material known as composite which has much superior property than
any one of the constituent materials.
- Fiberglass is an example of composite material which is a combination glass fibre
embedded within a polymeric material.
- Strength of the glass fibre and tricks ability from the polymer is acquired by
fiberglass.
- Other examples of composite materials are cement, concrete, plywood, metal etc.

8. 5.Semiconductors:- The materials whose electrical conductivity lies between
conductors and insulators are known as semiconductor.
-The electrical characteristics of these materials are extremely sensitive to the
presence of minute concentration of impurity atoms.
-Some of commonly conductors are silicone, germanium, gallium arsenide etc.
-These materials are very widely used in fabrication of electronic components such
as diodes, transistors, silicon-controlled rectifier, photocells etc.

9. 6.Biomaterials:- Biomaterials are employed in components implanted into the
human body for replacement of damage or disease body parts.
-Material should not produce toxic substance and also are required to be
compatible with body tissues.
-Metals, polymers, composites, ceramics, semiconductors can be used as
biomaterials which possess the required characteristics.

10. Selection of criteria Engineering Materials
Selection of a proper material is not an easy job.
It is difficult, lengthy and expensive task to select a proper material. The best material is one
which will serve the desired objectives at minimum cost.
The following factors should be considered while selecting a material.
1. Availability
2. Cost
3. Properties of materials
4. Manufacturing considerations
5. Environmental considerations

11. 1. Availability: The material should be readily available in the market in large
enough quantities satisfy the requirements,
2. Cost: The components which is being design can be manufactured by using
several alternative materials, which can satisfy the objectives.
- The material which will involve minimum cost should be selected. These are two
aspects the cost of the material and cost of processing the material, to convert it
into finished product.
-It so happened that cost of material is low, but the processing cost can be higher.
-Looking into do these two aspects the material should be selected having minimum
cost

12. 3. Properties of Material: The material to be selected for a component should
possess the Desire properties.
-Depending on the service condition and the functional requirements different
properties are taken into account and a suitable material is selected.
4. Manufacturing consideration: Manufacturing considerations of a material is
one of the important factors while selecting the material for the component.
-Sometimes it may be possible that higher cost of material can be easily transfer to
finished product whereas lower cost material will require most processing cost.
-Where product is of complex shape stability of a material becomes important.
Casting, welding, rolling, forging, extrusion, drawing and machining processes
govern the selection of a material.

13. 5. Environmental considerations: While selecting materials for any component
the environmental aspects are required to be given due to consideration.
-The selected material should not create pollution.
-The final product, device or appliance should be designed such that during its
lifetime, any effect on the environment is minimum furthermore at the end of its
like that, at best provision be made for recycling of materials of the component or
at least for their disposal with little ecological degradation.

14. Applications of materials
1. Grey cast iron: - machine tools body, cylinder block, pipes and pipe fittings, agriculture
instrument, flywheel, frames, gear pumps
2. White cast iron:- raw material in production of malleable cast iron, inferior casting
3. Malleable cast iron: plough, spares, chilled rolls, connecting rods, crusher Jaws, stamping
shoes, car wheels etc.
4. Alloy cast iron: Cylinders, cylinder liner, pipes, parts of hydraulic machinery, break drums
etc.
5. Plain Carbon Steel:-
i) Low Carbon Steel(mild steel)- nails, rivets, chain links, cams, light duty gears, shafts, car
bodies, pipes, tubes etc.
ii) Medium Carbon Steel- axles, connecting rod, crankshaft, gears, die blocks, wheel drum
etc.
iii) High carbon Steels- railway wheel, hammer, punches, dies, screwdrivers, wire ropes, razor
blades, scissors, taps, tools etc.

15. 6. Tool steel:- cutting tools, reamers, spanners, twist drills, chisels, pneumatic tools, taps,
punches, dies, roll for Rolling Mills etc,
7. Stainless steel:- utensils, turbine blades, surgical and Dental instruments, valves,
springs, cutlery, gears, ball bearing etc.
8. Heat resistant Steel:- aero plane engine valve, marine engine valve, piping steam
plants super heater tubes, gas turbine disc and blades etc.
9. Spring steel:- springs, laminated spring for railway Wagons, carriages, trucks etc.
10. Nickel Chrome Steel:- crankshaft, axles, pipe tubes, piston rod
11. Nickel Chrome molybdenum Steel:- structure purpose
12. Aluminium and aluminium alloys:- wires, household utensils, tubes, plates,
automobile components, musical instrument, worm wheels, gears, pump parts, aircraft,
refrigeration, cooking utensils etc.
13. Copper and copper alloys:- electrical cable wire, household utensils, valves, wire
drawing.

16. 14. Gun metal:- casting guns, boiler fittings, bushes, bearings
15. Zinc and Zinc alloys:- washing machines, refrigerators, radiator, television.
16. Lead and lead alloys:- sheaths of electrical cable, lining for Acid tanks,
Solders, water pipes etc.
17.Magnesium and its alloys:- fireworks, radio tubes, aircraft and missile
industry, portable machinery and instruments etc.
18. Titanium and alloys:- aircraft frames, gas turbine, blades, missile fold tanks,
process equipment, vessels etc.
19. Nickel and alloys:- condenser tubes, seawater exposed parts, food handling
parts, exhaust manifold of aircraft engine, electrical resistance wire for electric
furnace, gas turbine engine etc.
20. Tin and alloys:- foils protective coating, sheets, solder etc.

17. Heat treatment process
-Heat treatment is defined as heating and cooling operation applied to metals and alloys in
solid state in order to obtain the desired properties. Heat treatment is carried out as to have
changes in Mechanical properties of the metal and alloys. Normally Steels are subjected to
heat treatment for the purpose of a chewing one or more of the following objectives.
i. To increase the hardness
ii. To improve ductility
iii. To relieve the residual stress which are set up after cold or hot working.
iv. To refine the grain size.
v. To improve the electric and magnetic properties.
vi. To improve wear resistance, corrosion resistance and shock resistance.

18. Heat treatment process can be classified as
1. Annealing
2. Normalizing
3. Hardening
4. Tempering

19. 1. Annealing:- this process carried out for steel consists of heating the Steel to a
temperature in the range of 750 degree Celsius to the 950 degree Celsius holding it at this
temperature for the sufficient time and thereafter slow cooling in the Furnace.
-Annealing does not produce any new structure by phase transformation but produce new
grains of the same structure.
-Annealing process is carried out to attain one or more of the following purpose
i. To relieve residual stress setup during hot or cold working
ii. Improve machinability.
iii. Improve ductility and toughness.
iv. Refine grain size.
v. Remove entrapped gases.
vi. Alter electrical, magnetic or other physical properties.
The annealing process can be classified as full annealing, process annealing, spheroids
annealing and diffusion annealing.

20. 2. Normalizing:- this process carried out for a steel consists of heating the Steel
to a temperature in the range of 7 50 degree to 975 degree Celsius holding it for a
short period There after cooling it in steel air at room temperature, the main
objective of normalizing process is to have grain refinement and uniform
condition in steel, the main objectives of normalizing process are
i. To refine grain structure, improve machinability and tensile strength.
ii. To remove strain cause by cold working process.
iii. To improve the certain mechanical and electrical properties.

21. 3. Hardening:- the hardening process for steel consists of heating the material at
temperature job 750 degree Celsius to the 950 degree Celsius holding it for a
considerable period of thereafter cooling at a faster rate by quenching the material
in oil or water. It is very commonly for almost all the tools, various parts made of
Steel. The main objectives of hardening process are
i. To improve hardness.
ii. To improve tensile strength.
iii. To improve wear resistance.

22. 4. Tempering:- This is a process carried out after hardening in order to decrease
brittleness, restore ductility and improve toughness. After hardening process
increase in hardness results in reduction ductility, increase in internal strains
which makes the material unsafe for use.
-Tempering follows hardening in order to avoid problems of cracking and
distortion.
-The tempering process consists of heating of the hardened material to a
temperature in the range from room temperature to 400 degree Celsius, holding it
for a considerable period and there after slow cooling.

23. Manufacturing processIntroduction
• Manufacturing process can be defined as the process which converts input raw material
into useful output product.
• In Modern era the process are developed and are being developed which will convert raw
material into useful product with higher producing rate, better surface finish, better
accuracy etc.
• These processes have been developed with a view to have automation so as to reduce the
time required for the work to be carried.
• This better method have gradually transferred more skill to machine, which reduced the
manual labour.
• However, the need of study the fundamental manufacturing process need not be under
estimated. In the chapter study of different manufacturing process deal with.

24. Classification of manufacturing processes
• The various Metals used in industries are first obtained in the form of ores.
• These ores subjected to a suitable reducing and refining process to convert it into
molten metal form.
• This molten metal is poured into moulds as to get ingots.
• This ingots are for the process by using one or the Other manufacturing
processes so as to give it the desired shape and size.
• The process is used for conversion of ingots into useful products are classified in
five groups.

25. I) primary shaping processes:- the primary shaping process commonly used in
industries are as casting, forging, rolling, drawing, bending, extrusion, squeezing,
shearing, pinning, crushing, fawning, piercing.
II) machining processes:- in order to give desired size and shape the cast, rolled,
forged raw material is machined. The various machining operations are as
turning, drilling, shaping, planning, milling, threading, boring, sawing, hobbing,
grinding, broaching, slotting, knurling etc
III) surface finishing processes:- either removing very less amount of material
or by adding small amount of material, the product is given better surface finish
by carrying out different surface finishing processes like superfinishing, lapping,
honing, burnishing polishing etc.

26. IV) joining processes:- metal parts are joined together using joining processes.
The joining processes use are welding. Soldering, brazing etc.
V) process of bringing change in properties:- these are the processes which are
used to import certain specific properties to the metal so as to make them suitable
for a specific operation or use. The different processes used to change physical
properties of the metals are as heat treatment, hot working, cold working, shot
peening etc.

27. Casting
• Casting is one of the oldest method known to human being. Casting process normally
means pooling of molten metal into a refractory mould. This mould is provided with a
cavity of the shape to be made. Then the molten metal is allowed to solidify. The solitary
fired metal object is removed from the mould by breaking the mould or taking it apart.
• Very good example of the casting in old days can be the famous Iron Pillar presently located
near to Qutub Minar in New Delhi. It is 7.2m long and is made of pure malleable iron.
• Applications of casting process:- Machine tool beds, cylinder blocks, pistons, piston
rings, wheels, housing, water supply pipes, bells, carburator, crankcase, hubs, brackets, fuel
pump, gears, flywheels, gun barrels, brake drum etc

28. Working principle of sand casting.

29. • The six basic steps in making sand castings are,
(i) Pattern making, (ii) Core making, (iii) Moulding, (iv) Melting and
pouring, (v) Cleaning
i)Pattern making
- Pattern: Replica of the part to be cast and is used to prepare the mould cavity. It
is the physical model of the casting used to make the mould. Made of either wood
or metal.
-The mould is made by packing some readily formed aggregate material, such as
moulding sand, surrounding the pattern. When the pattern is withdrawn, its
imprint provides the mould cavity. This cavity is filled with metal to become the
casting.
- If the casting is to be hollow, additional patterns called ‘cores’, are used to form
these cavities.

30. ii)Core making
Cores are placed into a mould cavity to form the interior surfaces of castings. Thus the
void space is filled with molten metal and eventually becomes the casting.
iii)Moulding
-Moulding is nothing but the mould preparation activities for receiving molten metal.
-Moulding usually involves: (i) preparing the consolidated sand mould around a pattern
held within a supporting metal frame, (ii) removing the pattern to leave the mould cavity
with cores.
-Mould cavity is the primary cavity.
-The mould cavity contains the liquid metal and it acts as a negative of the desired
product. The mould also contains secondary cavities for pouring and channelling the
liquid material in to the primary cavity and will act a reservoir, if required.

31. iv)Melting and Pouring
The preparation of molten metal for casting is referred to simply as melting. The
molten metal is transferred to the pouring area where the moulds are filled.
v)Cleaning
Cleaning involves removal of sand, scale, and excess metal from the casting.
Burned-on sand and scale are removed to improved the surface appearance of the
casting. Excess metal, in the form of fins, wires, parting line fins, and gates, is
removed. Inspection of the casting for defects and general quality is performed.

32. Sand Casting Applications
-Sand casting is extensively used, for cast iron and steel parts of medium and
large size where surface smoothness and dimensional precision are the main
concerns.
-Sand casting is also used to make large parts in material like bronze, brass,
aluminum, etc.
-Also used for casting sculptures which can have a certain amount of rough
surface finish

33. Forging
Forging is a manufacturing process in which metal is shaped by impact or
with very high pressure. The metal is squeeze to attend the desired shape and
this requires the metal to be very hot and in plastic condition.
1. Hot forging:- hot forging is the controlled plastic deformation of metal at
elevated into a predetermined size or shape by using compressive forces.
Compressive forces are exerted through some type of die by hammer, a Press
or by forging machine.

34. Types of hot forging
i) hammer or Smith forging
-In this process parts are heated in a Smiths open furnace and forced to be
required shape with hand tools without the aid of die.
-The process is slow accuracy or finish depends on the skill of operator.
-It is used for production of agriculture tools maintenance work etc.

35. ii) drop forging
-In this process specified weight hammer is raised to a definite height and is
allowed to fall freely under its own weight as shown in figure.
-The upper half of a die is mounted on the raise hammer and the metal is placed
over the lower half of the die.
-In a drop forging process, impression dies are used to control the shape and size.
-The hammer used maybe of gravity type or hydraulic type.

36. iii. Upset forging
-Upset forging consists of gripping of hot parts between two dies and striking the
protruding end with another die.
-Upset forging is used for manufacturing of gear blanks, flanges, an axle, valves
etc.

37. iv) Press forging
-Forging of parts by press, involve close
squeezing of plastic metal. Hydraulic for
mechanical presses are used to carry out the
operation.
-The operation is faster.
-The whole operation is carried out in a single
squeezing operation.
-Deep penetration is obtained because enough
time is allowed to the metal to flow.
-More complicated shapes with better
dimensional accuracy can be forged.

38. vi) roll forging
-The figure shows one of the roll forging
operation.
-The workpiece is a fed against the set of rollers.
The rollers are given particular shape at the
Periphery as per the requirement.
-The rollers applied the force on the product and
also rotate.
-The required size is obtained in more than one
stages.
-Roll forging is used to produce the livers, leaf
Springs, cutlery items, scissors, axles etc.

39. 2. Cold forging
-In cold forging process the metal is performed by application of impact
forces at room temperature.
-The metal flows due to impact force and required shape is obtained by using
suitable dies.
-From coiled wire nails, rivets, small bolts and screws are manufactured by
this method.

40. Welding
• Wedding is a process in which two similar metals are permanently join together
through localised fusion due to suitable application of heat and pressure.

41. Arc Welding

42. -Arc welding is the fusion of two pieces of metal by an electric arc between the
pieces being joined – the work pieces – and an electrode that is guided along the
joint between the pieces.
-The electrode is either a rod that simply carries current between the tip and the
work, or a rod or wire that melts and supplies filler metal to the joint.
-The basic arc welding circuit is an alternating current (AC) or direct current (DC)
power source connected by a “work” cable to the work piece and by a “hot” cable to
an electrode.
- When the electrode is positioned close to the work piece, an arc is created across
the gap between the metal and the hot cable electrode.
- An ionized column of gas develops to complete the circuit.

43. -The arc produces a temperature of about 3600°C at the tip and melts part of the metal
being welded and part of the electrode.
-This produces a pool of molten metal that cools and solidifies behind the electrode as it
is moved along the joint.
-There are two types of electrodes.
-Consumable electrode tips melt, and molten metal droplets detach and mix into the weld
pool.
-Non-consumable electrodes do not melt. Instead, filler metal is melted into the joint
from a separate rod or wire.
-The strength of the weld is reduced when metals at high temperatures react with oxygen
and nitrogen in the air to form oxides and nitrides.
-Most arc welding processes minimize contact between the molten metal and the air with
a shield of gas, vapour or slag.
-Granular flux, for example, adds deoxidizers that create a shield to protect the molten
pool, thus improving the weld.

44. Soldering
Introduction:
Soldering is also a metal joining process, but it is performed at lower temperature at about
400 degree. The heating is with the help of soldering iron(gun). And the soldering metal
(filler metal) tin and lead is kept at joining position heated with gun in presence of flux, salt
Ammonia zinc chloride. Soldering metal Nails and the joint is formed. Soldering is used in
electronic circuit electrical circuit for joining wires.
Definition: -The joining of metals using a filler material of a lower melting point than that
of the parent metals to be joined.
Soldering Process:
1. Heat both items by applying the soldering iron to the copper pad and the component lead.
2. Continue heating and apply a few millimeters of solder. Remove the iron and allow the
solder joint to cool naturally.
3. It only takes a second or two to make the perfect joint, which should appear shiny.

45. What is Flux?
-Flux is a chemical compound.
-Is applied and shields the joint surface from air and prevents oxide formation.
-Although flux will dissolve and absorb oxides.
Applications:
-Soldering is use in electronics and in jewelry metalwork.
-Some refrigeration components are often assembled and repaired by the higher
temperature silver soldering.
-It can also be used as a semi-permanent patch for a leak in a container or cooking
vessel.

46. Advantages of Soldering:
1. Low power is required.
2. Low process temperature.
3. Microstructure is not affected by heat.
4. Easily automated process.
5. Dissimilar materials may be joined.
6. High variety of materials may be joined.
7. Thin wall parts may be joined.
Disadvantages of soldering:
1. Large sections cannot be joined.
2. Fluxes may contain toxic components.
3. Soldering joints can not be used in high temperature applications.
4. Low strength of joints.
5. Careful removal of the flux residuals is required in order to prevent corrosion.

47. Brazing
-Brazing is also a metal joining process but it different from welding.
- Brazing temperature is less than the welding.
- Joint formed is of lower strength.
- Base metal is not heated to fusion temperature.
- Filler metal is must in brazing. Brazing alloy is melted and put into the joint gap.
- Brazing alloy is used in copper zinc combination.
Advantages of Brazing:
1. Any metals can be joined including dissimilar metals.
2. Certain brazing methods can be performed quickly.
3. Brazing can be applied to join thin-walled parts that can’t be welded.
4. In general, less heat and power are required than in fusion welding.

48. Disadvantages of Brazing:
1. Joint strength is generally less than that of a welded joint.
2. Although strength of a good brazed joint is greater than that of the filler metal it is
likely to be less than that of the base metals.
3. High service temperatures may weaken a brazed joint
4. The colour of the metal in brazed joint may not match the colour of the base metal
parts

49. Thank You…